TSB's

Leaky crossover

Coolant leaks may be a complaint on certain GM vehicles, caused by a leaking gasket between the coolant crossover pipe and the front of the right (rear side) cylinder head. Affected vehicles include:

-          2006-2007 Buick Terraza

-          2009-2010 Buick Lucerne

-          2006-2007 Chevy Monte Carlo and Uplander

-          2006-2010 Chevy Impala and Malibu

-          2006-2007 Pontiac Montana SV6

-          2006-2009 Pontiac G6

-          2006-2007 Saturn Relay

-          2007-2009 Saturn AURA

-          2008-2009 Saturn VUE

(with 3.5 or 3.9 engine)

Replace the coolant crossover pipe gaskets with updated service replacement gaskets. There are three coolant crossover designs. The second design crossover started during the 2008 model year. The second design crossover features an access hole for a cylinder head plug on the rear bank (Bank 1). This crossover uses the three mounting hole gasket. There are two different second-design crossovers (see photos).

The first design crossover does not feature a hole in the bank area. This crossover uses the four hole mounting gasket.

Before installing the new gaskets, make sure that the mating surfaces on the crossover manifold and cylinder head are clean and that no oil or oil residue exists.

P/N                DESCRIPTION

12623852    Gasket first and second design, Bank 1

12623853    Gasket second design (three mounting holes)

126577704  Gasket first design (four mounting holes)

Two versions of the second design exist (example 1).
<p>Two versions of the second design exist (example 1).</p>

The other version of the second design (example 2). Note the access hole in each of the two second-design crossover manifolds.
<p>The other version of the second design (example 2). Note the access hole in each of the two second-design crossover manifolds.</p>

The first design does not feature an access hole.
<p>The first design does not feature an access hole.</p>

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